Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Calorimetric, Dielectric, and Neutron Diffraction Studies on Phase Transitions in Ordinary and Deuterated Acetone Crystals (1995)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 14167-14173 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100038a059
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Neutron diffraction and calorimetric studies of methylammonium iodide (1992)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 48 (1992), S. 329-336 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108768192000260
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Thermally-induced Transition in Aqueous Solution of Cationic Surfactant Containing Aromatic Ring (1999)
    Springer
    Journal of thermal analysis and calorimetry 57 (1999), S. 669-678 
    Details
    ISSN: 1572-8943
    Keywords: enthalpy of formation ; intermolecular compound ; rod-like micelles ; surfactant with additive ; thermal transition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Heat capacities of aqueous solutions of cetyltrimethylammonium (CTA) salicylate, of CTA m-hydroxybenzoate and of CTA p-hydroxybenzoate were measured using a scanning microcalorimeter. Only the salicylate solution exhibited heat-capacity anomaly around 330 K, depending on the heating rate. The transition enthalpy was 3.5±0.2 kJ mol−1, which was similar to that observed in solution of 1:1 intermolecular compound between CTA bromide (CTAB) and o-iodophenol (OIPh). The enthalpy of formation ΔHf of the 1:1 intermolecular compound from CTAB and OIPh was determined by measuring the enthalpies of solution of the relevant crystals into ethanol. Positive value ΔfH=3.0±0.3 kJ mol−1 was explained from a large difference between the heat capacities of the 1:1 compound and 1:1 mixture of the component crystals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010168010761
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Low-temperature heat capacity of urea (1993)
    Springer
    International journal of thermophysics 14 (1993), S. 149-158 
    Details
    ISSN: 1572-9567
    Keywords: Debye temperature ; heat capacity ; thermodynamic functions ; urea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The heat capacity of urea was measured with an adiabatic calorimeter in the temperature range 15–310 K. The data were extrapolated to 0 K by a model function to derive some standard thermodynamic functions including the enthalpy increments Δ 0 T H, the entropy increments Δ 0 T S, and the Giauque function (=Δ 0 TS −Δ 0 T H/T). A simple model for the reproduction of the experimental heat capacities of urea, based on the Debye and Einstein functions, is described. The Debye characteristic temperature determined in this way was compared with those calculated from properties other than the heat capacity. Any positive evidence of a suggested phase transition in urea around 190 K was not observed in the present heat capacity measurements. Possible existence of a phase with a Gibbs energy lower than that realized in the present investigation is discussed briefly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00522668
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Calorimetric study of phase transitions in the thiourea 1,1,2,2-tetrachloroethane clathrate compound (1992)
    Springer
    Journal of thermal analysis and calorimetry 38 (1992), S. 1861-1872 
    Details
    ISSN: 1572-8943
    Keywords: calorimetric study ; clathrate compound ; heat capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Bei Temperaturen zwischen 13 und 330 K wurde die Wärmekapazität der Thioharnstoff-Einschlußverbindung von 1,1,2,2-Tetrachlorethan gemessen. Dabei wurden zwei Phasenumwandlungen festgestellt. Die Enthalpie- und Entropieänderungen der Umwandlungen betragen 5940 Jmol−1 und 28.1 JK−1·mol−1 für die Umwandlung bei 224 K und 2756 Jmol−1 bzw. 11.3 JK−1·mol−1 für die Umwandlung Bei 248 K. Aus den Entropiewerten der Umwandlung wird geschlossen, daß die Gastmoleküle in etwa dem gleichen Maße ungeordnet sind, wie in der reinen Flüssigkeit.
    Notes: Abstract Heat capacities of the thiourea clathrate compound of 1,1,2,2-tetrachloroethane, {(NH2)2CS}3(CHCl2)2, were measured at temperatures between 13 and 330 K. Two phase transitions were found. The enthalpy and entropy changes of the transition are 5940 J·mol−1 and 28.1 JK−1· mol−1 for the one occurring at 224 K and 2756 J·mol−1 and 11.3 JK−1·mol−1 for the other at 248 K. It is concluded from the transition entropy values that the guest molecules are orientionally disordered nearly to the same extent as in the neat liquid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01974680
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Heat capacity and transition phenomena of structure I and II trimethylene oxide clathrate hydrates (1992)
    Springer
    Journal of thermal analysis and calorimetry 38 (1992), S. 1921-1937 
    Details
    ISSN: 1572-8943
    Keywords: adiabatic calorimeter ; heat capacities ; trimethylene oxide clathrate hydrates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Heat capacities of structure I and II trimethylene oxide (TMO) clathrate hydrates doped with small amount of potassium hydroxide (x=1.8×10−4 to water) were measured by an adiabatic calorimeter in the temperature range 11–300 K. In the str. I hydrate (TMO·7.67H2O), a glass transition and a higher order phase transition were observed at 60 K and 107.9 K, respectively. The glass transition was considered to be due to the freezing of the reorientation of the host water molecules, which occurred around 85 K in the pure sample and was lowered owing to the acceleration effect of KOH. The relaxation time of the water reorientation and its distribution were estimated and compared with those of other clathrate hydrates. The phase transition was due to the orientational ordering of the guest TMO molecules accommodated in the cages formed by water molecules. The transition was of the higher order and the transition entropy was 1.88 J·K−1(TMO-mol)−1, which indicated that at least 75% of orientational disorder was remaining in the low temperature phase. In the str. II hydrates (TMO·17H2O), only one first-order phase transition appeared at 34.5 K. This transition was considered to be related to the orientational ordering of the water molecules as in the case of the KOH-doped acetone and tetrahydrofuran (THF) hydrates. The transition entropy was 2.36 JK−1(H2O-mol)−1, which is similar to those observed in the acetone and THF hydrates. The relations of the transition temperature and entropy to the guest properties (size and dipole moment) were discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01974686
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Thermal study of glass transitions in binary systems of simple hydrocarbons (1992)
    Springer
    Journal of thermal analysis and calorimetry 38 (1992), S. 1847-1860 
    Details
    ISSN: 1572-8943
    Keywords: DTA ; glass transitions ; hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Mittels DTA wurden Glasumwandlungserscheinungen von vier binären Systemen aus einfachen Kohlenwasserstoffen untersucht. Für alle Systeme wurde eine definitive Glasumwandlung beobachtet, wobei man eine monotone Beziehung zwischen der Glasumwandlungstemperatur (T g) und der Zusammensetzung (x) erhielt. Die Konzentrationsabhängigkeit vonT g wurde hinsichtlich der Entropietheorie auf der Grundlage des regulären Lösungsmodelles analysiert. Die Prognose konnte die Resultate nicht reproduzieren, nur das System (1-Buten)x(1-Penten)1−x. Diese Diskrepanz wird mit der Abweichung der Systeme von einer regulären Lösung erklärt und die zusätzliche Konfigurationsentropie Sc E wurde als Funktion der Konzentration geschätzt. Außerordentlich hohe Werte für 5c E wurden bei den Systemen (Propen)x(Propan)1−x und (Propen)x(Penten)1−x erhalten.
    Notes: Abstract Glass transition phenomena of four binary systems composed of simple hydrocarbons were studied by means of the differential thermal analysis (DTA). For all the systems, a definite glass transition was observed and a monotonous relation between the glass transition temperature (T g) and composition (x) was obtained. The composition dependence ofT g was analyzed in terms of the entropy theory based on the regular solution model. The theoretical prediction could not reproduce our results other than (1-butene)x(1-pentene)1−x system. This disagreement is considered to be due to deviations of the present systems from the regular solution, and the accompanying excess configurational entropy Sc E was estimated as a function of composition. Extraordinarily large values of S c E ? were obtained for (propene)x(propane)1−x and (propene)inx(1-pentene)1−x systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01974679
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Dielectric study on pure and KOH-doped tetrahydrofuran clathrate hydrates (1990)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 8 (1990), S. 33-44 
    Details
    ISSN: 1573-1111
    Keywords: Dielectric permittivity ; phase transition ; doping effect ; relaxation phenomenon ; tetrahydrofuran clathrate hydrate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Complex dielectric permittivities of pure and KOH-doped (x = 1.8 x 10−4) tetrahydrofuran clathrate hydrates were measured in the temperature range 20–260 K and in the frequency range 20 Hz-1 MHz. The relaxation time of the water reorientational motion was found to decrease drastically as a result of the doping; e.g., the relaxation time of the doped sample was 10−9 times shorter than that of the pure sample at 70 K. The activation enthalpy of the motion was reduced to 7.4 kJ mol−1. On cooling the crystal, the value ofɛ′ decreased suddenly at the 62 K phase transition to theε ∞2 value of the pure sample and at the same timeɛ″ disappeared. No dispersion effect due to the guest reorientation was observed below the transition. These data indicate that both the host and guest molecules become ordered or, at least, change their mobility drastically. In the pure sample, a relaxation phenomenon ofε 02 was found around the glass transition region. The relaxation times agreed well with those derived from the enthalpy of relaxation in a calorimetric study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01131286
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Calorimetric study of phase transitions in the thiourea carbon tetrachloride inclusion compound (1990)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 9 (1990), S. 243-251 
    Details
    ISSN: 1573-1111
    Keywords: Thiourea inclusion compound ; phase transition ; entropy of transition ; orientational disorder ; guest-guest interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Heat capacities of the inclusion compound (thiourea)3.00CCl4 have been measured in the temperature range 15–300 K. A first-order phase transition was found at 41.3 K and a second-order transition at 67.17 K. The enthalpy and entropy of the transition are 149 J mol−1 and 3.7 J K−1 mol−1 for the former, and 241 J mol−1 and 3.9 J K−1 mol−1 for the latter. A divergent expression ΔC = A{(T c −T)/T c} −α was fitted to the excess heat capacity of the upper phase transition. The best-fit parameters wereA = 7.4 J K−1 mol−1,T c = 67.166 K and α = 0.31. Possible types of molecular disorder in the high temperature phase are discussed in relation to the transition entropy and the molecular and site symmetries of the guest molecule. The heat capacity of the lowest temperature phase was unusually large and may indicate the existence of very low frequency vibrational modes or labile configurational excitation of the guest molecule. Standard thermodynamic functions were calculated from the heat capacity data and are tabulated in the appendix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01053122
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Heat capacity and glass transition of ethylene oxide clathrate hydrate (1990)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 8 (1990), S. 45-58 
    Details
    ISSN: 1573-1111
    Keywords: Heat capacity ; glass transition ; clathrate hydrate ; ethylene oxide hydrate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The heat capacity of structure I ethylene oxide clathrate hydrate EO-6.86 H2O was measured in the temperature range 6–300 K with an adiabatic calorimeter. The temperature and enthalpy of congruent melting were determined to be (284.11 ± 0.02) K and 48.26 kJ mol−1, respectively. A glass transition related to the proton configurational mode in the hydrogen-bonded host was observed around 90 K. This glass transition was similar to the one observed previously for the structure II tetrahydrofuran hydrate but showed a wider distribution of relaxation times. The anomalous heat capacity and activation enthalpy associated with the glass transition were almost the same as those for THF-hydrate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01131287
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...